package LeetCode.leetcode;

/**
 * 正则表达式 动态规划
 * dp[i][j]表示s从0-i字符串，p从0-j字符串的匹配结果
 * @author: leiwenkang02@meituan.com
 * @date: 2018/9/19
 * @time: 19:06
 */
public class Test10正则表达式匹配 {
    public static void main(String[] args) {
        System.out.println(isMatch("aab", "c*a*b"));
    }

    public static boolean isMatch(String s, String p) {
        if (s == null || p == null) {
            return false;
        }
        boolean[][] dp = new boolean[s.length() + 1][p.length() + 1];
        dp[0][0] = true;
        for (int i = 0; i < p.length(); i++) {
            if (p.charAt(i) == '*' && dp[0][i - 1]) {
                dp[0][i + 1] = true;
            }
        }
        for (int i = 0; i <s.length(); i++) {
            for (int j = 0; j < p.length(); j++) {
                if (p.charAt(j) == '.') {
                    dp[i + 1][j + 1] = dp[i][j];
                }
                if (p.charAt(j) == s.charAt(i)) {
                    dp[i + 1][j + 1] = dp[i][j];
                }
                if (p.charAt(j) == '*') {
                    if (p.charAt(j-1) != s.charAt(i) && p.charAt(j-1) != '.') {
                        dp[i+1][j+1] = dp[i+1][j-1];
                    } else {
                        dp[i+1][j+1] = (dp[i+1][j] || dp[i][j+1] || dp[i+1][j-1]);
                    }
                }
            }
        }
        return dp[s.length()][p.length()];

    }

}
